eBay Amp 650W AB Class - Someone Try It ?

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#122
Especially true when you you get something wrong and release the very expensive silicon smoke 🙂

I afraid the customs men are greedy in all countries now days I sometimes feel that UK PLC is expecting me pay back the whole of the national debt. ;-(
 
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#123
Earthquake said:
Especially true when you you get something wrong and release the very expensive silicon smoke 🙂

I afraid the customs men are greedy in all countries now days I sometimes feel that UK PLC is expecting me pay back the whole of the national debt. ;-(
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Current limited supplies and zero bias on first power up helps reduce the chances of smoke release.

On the customs front, even though I pay the VAT, it doesn't help the national debt.
 
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#124
AudioSan said:
don't play the game if you can't take the pain.
i cant see how you need to pay 100% taxes. there is only 18%VAT where you live.
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85euros is customs processing fee and tax is plus 20% on all shipping included
:smash:
take a hummer and smash it 🙂

So after all I am forced to buy transistors from local store 🙁

other option is scrap the project and make D class amp but I am curious about sound quality of class D:smash:
 
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#127
thats at least 15 orders by the time you have all the parts for the amp. how much have you paid in shipping by the time you are done? a hell lot more then 85€ so that is pointless. think a little longer. is not many that have free shipping on smal orders. exept ebay. but then you are at big risk to get fake parts.
 
#128
The funny thing is that when customs inpector see more than one transistor lets say 10pc than no matter if its less than 50euro they will charge tax and customs processing fee
I will probably buy transistors from local store and hammer 1 pcs to test strength 🙂 hfe 🙂 power 🙂
thats the only option I have for now
I bought 20pcs MJ15003 Motorola from local store for other amp it says ON marking on the case but allso M for motorola is that onsemi? But they are ok they are still working:smash:
 
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#130
mcd99uk said:
Current limited supplies and zero bias on first power up helps reduce the chances of smoke release.

On the customs front, even though I pay the VAT, it doesn't help the national debt.
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Oh yeah I agree about the current limited power supply and zero bias I was referring to the odd slip with either meter probes or screwdriver I don't suppose I'm the only builder that has done this especially when checking voltages around small signal transistors, one slip in the wrong place and poof exit all semiconductors even had the tops blow right off.
 
#131
Earthquake said:
Maybe you don't spends as much as we do on imported goods then!! ;-(
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Oh I do import a lot but regardless of the 20% they take, the rest of the money leaves the country and harms the "balance of payments". So 80% of the cash indirectly adds to the national debt. It's got to come from somewhere...

Earthquake said:
Oh yeah I agree about the current limited power supply and zero bias I was referring to the odd slip with either meter probes or screwdriver I don't suppose I'm the only builder that has done this especially when checking voltages around small signal transistors, one slip in the wrong place and poof exit all semiconductors even had the tops blow right off.
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Yep, been there done that many times. 😀 I'm into killing Vertical MOSFETs at present.
 
#132
mcd99uk said:
Oh I do import a lot but regardless of the 20% they take, the rest of the money leaves the country and harms the "balance of payments". So 80% of the cash indirectly adds to the national debt. It's got to come from somewhere...



Yep, been there done that many times. 😀 I'm into killing Vertical MOSFETs at present.
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Well I assume your either playing with some form of switching amp or power supplies then.
 
#133
Earthquake said:
Well I assume your either playing with some form of switching amp or power supplies then.
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No just trying to achieve a very fast output stage with error correction. Often end up with violent oscillations which seem to destroy the gate protection diodes and then the MOSFET gates. Oh well at least the IRFP240/9240 are not too expensive. Blowing stuff up is the best way to learn as long as you are making progress.
 
#137
Eliranba said:
how do i know if this is a full range ?
20-20khz

YJ 300W Mono LME49810 2SA1943 2SC5200 Amplifier Board | eBay
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wOw 10 chinese clone output transistors for only 300watts rms 70w per transistor You will need more that 10 for 300rms watts at 8 ohms
You will need like 16 or 20 chinese clone transistors for 300rms
But You can always replace them with original and the rest of the parts on the board because they are fake not genuine

this amp is like 150-200watts rms

take a look at real power transistor

http://www.irf.com/product-info/datasheets/data/irfp90n20dpbf.pdf

580watts each 😀

Why dont You make Your own amp with genuine parts that way You will know what You have
 
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#138
Cause i dont have the knowlage to design myself
(especially the pcb design)
i want a class ab 100-200-300w with ultralow thd
i have a psu half ready for the amp
i prefer a kit because i dont want to mess with a lot of mini parts like diodes resistors & transistors
i know its low grade parts in those kits
i will replace the caps if it needed...(i have a lot of salvage parts)
 
#140
Eliranba said:
......i want a class ab 100-200-300w with ultralow thd......i prefer a kit because i dont want to mess with a lot of mini parts like diodes resistors & transistors......(i have a lot of salvage parts)
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This is a very cheap design and product for the claimed power output. That's why people are attracted and a thread is started here.

Unfortunately, it is not ultralow distortion and the component quality won't really affect that but if you are happy with lower power, there are better designs by LJM, for example, that are complete, tested modules of 50-200W or more. Shop around, there are better designs with less cramped and thermally compromised output stages like this one has, which will need thicker PCB tracks and very thick aluminium heatsinks to conduct heat rapidly without local hot spots and failures when run at medium-high power.

High power designs absolutely need proper, integral (in-built) VI limit protection, tuned to the precise type, supply voltage and number of output devices, whether you like the idea for Hi-fi purity or not. Add-on relays and heat sensors are not enough to protect big and expensive amps adequately. If you don't really need such high power (and you won't unless you really wanted a PA amplifier or to entertain a lot of people outdoors), dont use a poorly designed little monster like this. 🙁
 
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